A multiple-input multiple-output (multiple-input multiple-output, MIMO) radio system can obtain diversity and array gains by means of transmit precoding and receive signal combination. A system that utilizes precoding may be expressed as:y=H{circumflex over (V)}s+n 
where y represents a vector of a received signal, H represents a channel matrix, {circumflex over (V)} represents a precoding matrix, s represents a vector of a transmitted symbol, and n represents a measurement noise.
Optimal precoding generally requires that channel state information (Channel State Information, CSI) is completely known by a transmitter. A commonly used method is that a user equipment (User Equipment, UE) or a mobile station (Mobile Station, MS) (hereinafter generally referred to as UE) quantizes instantaneous CSI and feeds back the CSI to a NodeB (NodeB), which includes a base station (Base station, BS), an access point (Access Point), a transmission point (Transmission Point, TP), or an evolved NodeB (Evolved Node B, eNB), where the evolved NodeB is generally referred to as an eNB. CSI information that is fed back by an existing Long Term Evolution (Long Term Evolution, LTE) R8 system includes information such as a rank indicator (Rank Indicator, RI), a precoding matrix indicator (Precoding Matrix Indicator, PMI), and a channel quality indicator (Channel Quality Indicator, CQI), where the RI and the PMI respectively indicate the number of layers used and a precoding matrix. A set of used precoding matrices is generally referred to as a codebook, where each precoding matrix is a codeword in the codebook. To reduce system costs and meet higher requirements on the system capacity and coverage, an active antenna system (AAS) is already widely deployed in practice. Compared with an existing base station antenna, the AAS further provides a degree of freedom in design for the vertical direction.
An existing 4-antenna codebook, which is designed based on Householder transformation, of an LTE R8 system and an existing 8-antenna codebook, which is designed based on dual codebooks, of an LTE R10 system are mainly designed for a horizontal antenna, but a degree of freedom of a vertical antenna is not considered. When the 4-antenna codebook and the 8-antenna codebook are directly used in deployment of an AAS base station antenna, system performance severely deteriorates.